Numerical Investigation of the Irreversible Behavior of GDL Under Cyclic Hygrothermal Loading

Abstract

Performances of proton exchange membrane fuel cells (PEMFCs) is impacted by the physical properties of the gas diffusion layer (GDL). These properties, including thickness and porosity, are irreversibly modified by diverse processes, notably by the clamping of the PEMFC or the swelling of the membrane during cell operation. This can result in irreversible deformation of the GDL, with consequent impact on the performance and durability of the PEMFCs. This phenomenon, which is difficult to apprehend experimentally, is also challenging to investigate numerically. An elastoplastic law related to the irreversible strain of the GDL after compression is proposed in this study and implemented in a finite element model. Variations in GDL’s properties during humidity and temperature cycles are studied depending on PEMFC clamping methods using numerical simulations. The influences of processing conditions, i.e. the membrane electrode assembly hot pressing process, on GDLs properties are also investigated numerically. The results demonstrate the necessity to take into account the evolution of the mechanical properties of PEMFC components, with a significant influence of clamping process, life load and hot pressing process on the physical properties of the GDL as thickness, porosity, or intrusion in the gas channels.